Patchwork [PATCH-v3,1:2,MTD,NAND] omap: Adding support for nand prefetch-read and post-write, in MPU mode.

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Submitter Singh, Vimal
Date July 13, 2009, 10:56 a.m.
Message ID <60361.192.168.10.89.1247482584.squirrel@dbdmail.itg.ti.com>
Download mbox | patch
Permalink /patch/29728/
State New
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Comments

Singh, Vimal - July 13, 2009, 10:56 a.m.
Patch updated for ' ioreadX / iowriteX and ioreadX_rep / iowriteX_rep' as per
David Brownell's comment. I updated 'omap_(read/write)_buf16' fucntions also
for this.

-vimal

This patch adds prefetch support to access nand flash in mpu mode.
This patch also adds 8-bit nand support (omap_read/write_buf8).
Prefetch can be used for both 8- and 16-bit devices.

Signed-off-by: Vimal Singh <vimalsingh@ti.com>
---

---
 arch/arm/mach-omap2/gpmc.c             |   63 ++++++++++++
 arch/arm/plat-omap/include/mach/gpmc.h |    4
 drivers/mtd/nand/Kconfig               |    8 +
 drivers/mtd/nand/omap2.c               |  161 +++++++++++++++++++++++++++++++--
 4 files changed, 226 insertions(+), 10 deletions(-)
Tony Lindgren - Aug. 10, 2009, 4:27 p.m.
* vimal singh <vimalsingh@ti.com> [090713 13:56]:
> Patch updated for ' ioreadX / iowriteX and ioreadX_rep / iowriteX_rep' as per
> David Brownell's comment. I updated 'omap_(read/write)_buf16' fucntions also
> for this.
> 
> -vimal
> 
> This patch adds prefetch support to access nand flash in mpu mode.
> This patch also adds 8-bit nand support (omap_read/write_buf8).
> Prefetch can be used for both 8- and 16-bit devices.
> 
> Signed-off-by: Vimal Singh <vimalsingh@ti.com>

Sorry for the delay. I've looked at the GPMC part, and that now looks OK
to me. So I'm OK for this to get integrated via the MTD list.

Acked-by: Tony Lindgren <tony@atomide.com>


> ---
> 
> ---
>  arch/arm/mach-omap2/gpmc.c             |   63 ++++++++++++
>  arch/arm/plat-omap/include/mach/gpmc.h |    4
>  drivers/mtd/nand/Kconfig               |    8 +
>  drivers/mtd/nand/omap2.c               |  161 +++++++++++++++++++++++++++++++--
>  4 files changed, 226 insertions(+), 10 deletions(-)
> 
> Index: mtd-2.6/arch/arm/mach-omap2/gpmc.c
> ===================================================================
> --- mtd-2.6.orig/arch/arm/mach-omap2/gpmc.c
> +++ mtd-2.6/arch/arm/mach-omap2/gpmc.c
> @@ -57,6 +57,11 @@
>  #define GPMC_CHUNK_SHIFT	24		/* 16 MB */
>  #define GPMC_SECTION_SHIFT	28		/* 128 MB */
> 
> +#define PREFETCH_FIFOTHRESHOLD	(0x40 << 8)
> +#define CS_NUM_SHIFT		24
> +#define ENABLE_PREFETCH		(0x1 << 7)
> +#define DMA_MPU_MODE		2
> +
>  static struct resource	gpmc_mem_root;
>  static struct resource	gpmc_cs_mem[GPMC_CS_NUM];
>  static DEFINE_SPINLOCK(gpmc_mem_lock);
> @@ -386,6 +391,63 @@ void gpmc_cs_free(int cs)
>  }
>  EXPORT_SYMBOL(gpmc_cs_free);
> 
> +/**
> + * gpmc_prefetch_enable - configures and starts prefetch transfer
> + * @cs: nand cs (chip select) number
> + * @dma_mode: dma mode enable (1) or disable (0)
> + * @u32_count: number of bytes to be transferred
> + * @is_write: prefetch read(0) or write post(1) mode
> + */
> +int gpmc_prefetch_enable(int cs, int dma_mode,
> +				unsigned int u32_count, int is_write)
> +{
> +	uint32_t prefetch_config1;
> +
> +	if (!(gpmc_read_reg(GPMC_PREFETCH_CONTROL))) {
> +		/* Set the amount of bytes to be prefetched */
> +		gpmc_write_reg(GPMC_PREFETCH_CONFIG2, u32_count);
> +
> +		/* Set dma/mpu mode, the prefetch read / post write and
> +		 * enable the engine. Set which cs is has requested for.
> +		 */
> +		prefetch_config1 = ((cs << CS_NUM_SHIFT) |
> +					PREFETCH_FIFOTHRESHOLD |
> +					ENABLE_PREFETCH |
> +					(dma_mode << DMA_MPU_MODE) |
> +					(0x1 & is_write));
> +		gpmc_write_reg(GPMC_PREFETCH_CONFIG1, prefetch_config1);
> +	} else {
> +		return -EBUSY;
> +	}
> +	/*  Start the prefetch engine */
> +	gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x1);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(gpmc_prefetch_enable);
> +
> +/**
> + * gpmc_prefetch_reset - disables and stops the prefetch engine
> + */
> +void gpmc_prefetch_reset(void)
> +{
> +	/* Stop the PFPW engine */
> +	gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x0);
> +
> +	/* Reset/disable the PFPW engine */
> +	gpmc_write_reg(GPMC_PREFETCH_CONFIG1, 0x0);
> +}
> +EXPORT_SYMBOL(gpmc_prefetch_reset);
> +
> +/**
> + * gpmc_prefetch_status - reads prefetch status of engine
> + */
> +int  gpmc_prefetch_status(void)
> +{
> +	return gpmc_read_reg(GPMC_PREFETCH_STATUS);
> +}
> +EXPORT_SYMBOL(gpmc_prefetch_status);
> +
>  static void __init gpmc_mem_init(void)
>  {
>  	int cs;
> @@ -452,6 +514,5 @@ void __init gpmc_init(void)
>  	l &= 0x03 << 3;
>  	l |= (0x02 << 3) | (1 << 0);
>  	gpmc_write_reg(GPMC_SYSCONFIG, l);
> -
>  	gpmc_mem_init();
>  }
> Index: mtd-2.6/arch/arm/plat-omap/include/mach/gpmc.h
> ===================================================================
> --- mtd-2.6.orig/arch/arm/plat-omap/include/mach/gpmc.h
> +++ mtd-2.6/arch/arm/plat-omap/include/mach/gpmc.h
> @@ -103,6 +103,10 @@ extern int gpmc_cs_request(int cs, unsig
>  extern void gpmc_cs_free(int cs);
>  extern int gpmc_cs_set_reserved(int cs, int reserved);
>  extern int gpmc_cs_reserved(int cs);
> +extern int gpmc_prefetch_enable(int cs, int dma_mode,
> +					unsigned int u32_count, int is_write);
> +extern void gpmc_prefetch_reset(void);
> +extern int gpmc_prefetch_status(void);
>  extern void __init gpmc_init(void);
> 
>  #endif
> Index: mtd-2.6/drivers/mtd/nand/Kconfig
> ===================================================================
> --- mtd-2.6.orig/drivers/mtd/nand/Kconfig
> +++ mtd-2.6/drivers/mtd/nand/Kconfig
> @@ -80,6 +80,14 @@ config MTD_NAND_OMAP2
>  	help
>            Support for NAND flash on Texas Instruments OMAP2 and OMAP3 platforms.
> 
> +config MTD_NAND_OMAP_PREFETCH
> +	bool "GPMC prefetch support for NAND Flash device"
> +	depends on MTD_NAND && MTD_NAND_OMAP2
> +	default y
> +	help
> +	 The NAND device can be accessed for Read/Write using GPMC PREFETCH engine
> +	 to improve the performance.
> +
>  config MTD_NAND_TS7250
>  	tristate "NAND Flash device on TS-7250 board"
>  	depends on MACH_TS72XX
> Index: mtd-2.6/drivers/mtd/nand/omap2.c
> ===================================================================
> --- mtd-2.6.orig/drivers/mtd/nand/omap2.c
> +++ mtd-2.6/drivers/mtd/nand/omap2.c
> @@ -112,6 +112,16 @@
>  static const char *part_probes[] = { "cmdlinepart", NULL };
>  #endif
> 
> +#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
> +static int use_prefetch = 1;
> +
> +/* "modprobe ... use_prefetch=0" etc */
> +module_param(use_prefetch, bool, 0);
> +MODULE_PARM_DESC(use_prefetch, "enable/disable use of PREFETCH");
> +#else
> +const int use_prefetch;
> +#endif
> +
>  struct omap_nand_info {
>  	struct nand_hw_control		controller;
>  	struct omap_nand_platform_data	*pdata;
> @@ -124,6 +134,7 @@ struct omap_nand_info {
>  	unsigned long			phys_base;
>  	void __iomem			*gpmc_cs_baseaddr;
>  	void __iomem			*gpmc_baseaddr;
> +	void __iomem			*nand_pref_fifo_add;
>  };
> 
>  /**
> @@ -189,6 +200,38 @@ static void omap_hwcontrol(struct mtd_in
>  }
> 
>  /**
> + * omap_read_buf8 - read data from NAND controller into buffer
> + * @mtd: MTD device structure
> + * @buf: buffer to store date
> + * @len: number of bytes to read
> + */
> +static void omap_read_buf8(struct mtd_info *mtd, u_char *buf, int len)
> +{
> +	struct nand_chip *nand = mtd->priv;
> +
> +	ioread8_rep(nand->IO_ADDR_R, buf, len);
> +}
> +
> +/**
> + * omap_write_buf8 - write buffer to NAND controller
> + * @mtd: MTD device structure
> + * @buf: data buffer
> + * @len: number of bytes to write
> + */
> +static void omap_write_buf8(struct mtd_info *mtd, const u_char *buf, int len)
> +{
> +	struct omap_nand_info *info = container_of(mtd,
> +						struct omap_nand_info, mtd);
> +	u_char *p = (u_char *)buf;
> +
> +	while (len--) {
> +		iowrite8(*p++, info->nand.IO_ADDR_W);
> +		while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
> +						GPMC_STATUS) & GPMC_BUF_FULL));
> +	}
> +}
> +
> +/**
>   * omap_read_buf16 - read data from NAND controller into buffer
>   * @mtd: MTD device structure
>   * @buf: buffer to store date
> @@ -198,7 +241,7 @@ static void omap_read_buf16(struct mtd_i
>  {
>  	struct nand_chip *nand = mtd->priv;
> 
> -	__raw_readsw(nand->IO_ADDR_R, buf, len / 2);
> +	ioread16_rep(nand->IO_ADDR_R, buf, len / 2);
>  }
> 
>  /**
> @@ -217,13 +260,101 @@ static void omap_write_buf16(struct mtd_
>  	len >>= 1;
> 
>  	while (len--) {
> -		writew(*p++, info->nand.IO_ADDR_W);
> +		iowrite16(*p++, info->nand.IO_ADDR_W);
> 
>  		while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
>  						GPMC_STATUS) & GPMC_BUF_FULL))
>  			;
>  	}
>  }
> +
> +/**
> + * omap_read_buf_pref - read data from NAND controller into buffer
> + * @mtd: MTD device structure
> + * @buf: buffer to store date
> + * @len: number of bytes to read
> + */
> +static void omap_read_buf_pref(struct mtd_info *mtd, u_char *buf, int len)
> +{
> +	struct omap_nand_info *info = container_of(mtd,
> +						struct omap_nand_info, mtd);
> +	uint32_t pfpw_status = 0, r_count = 0;
> +	int ret = 0;
> +	u32 *p = (u32 *)buf;
> +
> +	/* take care of subpage reads */
> +	for (; len % 4 != 0; ) {
> +		*buf++ = __raw_readb(info->nand.IO_ADDR_R);
> +		len--;
> +	}
> +	p = (u32 *) buf;
> +
> +	/* configure and start prefetch transfer */
> +	ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
> +	if (ret) {
> +		/* PFPW engine is busy, use cpu copy method */
> +		if (info->nand.options & NAND_BUSWIDTH_16)
> +			omap_read_buf16(mtd, buf, len);
> +		else
> +			omap_read_buf8(mtd, buf, len);
> +	} else {
> +		do {
> +			pfpw_status = gpmc_prefetch_status();
> +			r_count = ((pfpw_status >> 24) & 0x7F) >> 2;
> +			ioread32_rep(info->nand_pref_fifo_add, p, r_count);
> +			p += r_count;
> +			len -= r_count << 2;
> +		} while (len);
> +
> +		/* disable and stop the PFPW engine */
> +		gpmc_prefetch_reset();
> +	}
> +}
> +
> +/**
> + * omap_write_buf_pref - write buffer to NAND controller
> + * @mtd: MTD device structure
> + * @buf: data buffer
> + * @len: number of bytes to write
> + */
> +static void omap_write_buf_pref(struct mtd_info *mtd,
> +					const u_char *buf, int len)
> +{
> +	struct omap_nand_info *info = container_of(mtd,
> +						struct omap_nand_info, mtd);
> +	uint32_t pfpw_status = 0, w_count = 0;
> +	int i = 0, ret = 0;
> +	u16 *p = (u16 *) buf;
> +
> +	/* take care of subpage writes */
> +	if (len % 2 != 0) {
> +		writeb(*buf, info->nand.IO_ADDR_R);
> +		p = (u16 *)(buf + 1);
> +		len--;
> +	}
> +
> +	/*  configure and start prefetch transfer */
> +	ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x1);
> +	if (ret) {
> +		/* PFPW engine is busy, use cpu copy method */
> +		if (info->nand.options & NAND_BUSWIDTH_16)
> +			omap_write_buf16(mtd, buf, len);
> +		else
> +			omap_write_buf8(mtd, buf, len);
> +	} else {
> +		pfpw_status = gpmc_prefetch_status();
> +		while (pfpw_status & 0x3FFF) {
> +			w_count = ((pfpw_status >> 24) & 0x7F) >> 1;
> +			for (i = 0; (i < w_count) && len; i++, len -= 2)
> +				iowrite16(*p++, info->nand_pref_fifo_add);
> +			pfpw_status = gpmc_prefetch_status();
> +		}
> +
> +		/* disable and stop the PFPW engine */
> +		gpmc_prefetch_reset();
> +	}
> +}
> +
>  /**
>   * omap_verify_buf - Verify chip data against buffer
>   * @mtd: MTD device structure
> @@ -658,17 +789,12 @@ static int __devinit omap_nand_probe(str
>  		err = -ENOMEM;
>  		goto out_release_mem_region;
>  	}
> +
>  	info->nand.controller = &info->controller;
> 
>  	info->nand.IO_ADDR_W = info->nand.IO_ADDR_R;
>  	info->nand.cmd_ctrl  = omap_hwcontrol;
> 
> -	/* REVISIT:  only supports 16-bit NAND flash */
> -
> -	info->nand.read_buf   = omap_read_buf16;
> -	info->nand.write_buf  = omap_write_buf16;
> -	info->nand.verify_buf = omap_verify_buf;
> -
>  	/*
>  	 * If RDY/BSY line is connected to OMAP then use the omap ready
>  	 * funcrtion and the generic nand_wait function which reads the status
> @@ -689,6 +815,23 @@ static int __devinit omap_nand_probe(str
>  								== 0x1000)
>  		info->nand.options  |= NAND_BUSWIDTH_16;
> 
> +	if (use_prefetch) {
> +		/* copy the virtual address of nand base for fifo access */
> +		info->nand_pref_fifo_add = info->nand.IO_ADDR_R;
> +
> +		info->nand.read_buf   = omap_read_buf_pref;
> +		info->nand.write_buf  = omap_write_buf_pref;
> +	} else {
> +		if (info->nand.options & NAND_BUSWIDTH_16) {
> +			info->nand.read_buf   = omap_read_buf16;
> +			info->nand.write_buf  = omap_write_buf16;
> +		} else {
> +			info->nand.read_buf   = omap_read_buf8;
> +			info->nand.write_buf  = omap_write_buf8;
> +		}
> +	}
> +	info->nand.verify_buf = omap_verify_buf;
> +
>  #ifdef CONFIG_MTD_NAND_OMAP_HWECC
>  	info->nand.ecc.bytes		= 3;
>  	info->nand.ecc.size		= 512;
> @@ -746,7 +889,7 @@ static int omap_nand_remove(struct platf
>  	platform_set_drvdata(pdev, NULL);
>  	/* Release NAND device, its internal structures and partitions */
>  	nand_release(&info->mtd);
> -	iounmap(info->nand.IO_ADDR_R);
> +	iounmap(info->nand_pref_fifo_add);
>  	kfree(&info->mtd);
>  	return 0;
>  }
> 
>
vimal singh - Aug. 11, 2009, 5:45 a.m.
On Mon, Aug 10, 2009 at 9:57 PM, Tony Lindgren<tony@atomide.com> wrote:
> * vimal singh <vimalsingh@ti.com> [090713 13:56]:
>> Patch updated for ' ioreadX / iowriteX and ioreadX_rep / iowriteX_rep' as per
>> David Brownell's comment. I updated 'omap_(read/write)_buf16' fucntions also
>> for this.
>>
>> -vimal
>>
>> This patch adds prefetch support to access nand flash in mpu mode.
>> This patch also adds 8-bit nand support (omap_read/write_buf8).
>> Prefetch can be used for both 8- and 16-bit devices.
>>
>> Signed-off-by: Vimal Singh <vimalsingh@ti.com>
>
> Sorry for the delay. I've looked at the GPMC part, and that now looks OK
> to me. So I'm OK for this to get integrated via the MTD list.
>
> Acked-by: Tony Lindgren <tony@atomide.com>
>

Can you give your ack to below patch too?

http://lists.infradead.org/pipermail/linux-mtd/2009-July/026373.html

>
>> ---
>>
>> ---
>>  arch/arm/mach-omap2/gpmc.c             |   63 ++++++++++++
>>  arch/arm/plat-omap/include/mach/gpmc.h |    4
>>  drivers/mtd/nand/Kconfig               |    8 +
>>  drivers/mtd/nand/omap2.c               |  161 +++++++++++++++++++++++++++++++--
>>  4 files changed, 226 insertions(+), 10 deletions(-)
>>
>> Index: mtd-2.6/arch/arm/mach-omap2/gpmc.c
>> ===================================================================
>> --- mtd-2.6.orig/arch/arm/mach-omap2/gpmc.c
>> +++ mtd-2.6/arch/arm/mach-omap2/gpmc.c
>> @@ -57,6 +57,11 @@
>>  #define GPMC_CHUNK_SHIFT     24              /* 16 MB */
>>  #define GPMC_SECTION_SHIFT   28              /* 128 MB */
>>
>> +#define PREFETCH_FIFOTHRESHOLD       (0x40 << 8)
>> +#define CS_NUM_SHIFT         24
>> +#define ENABLE_PREFETCH              (0x1 << 7)
>> +#define DMA_MPU_MODE         2
>> +
>>  static struct resource       gpmc_mem_root;
>>  static struct resource       gpmc_cs_mem[GPMC_CS_NUM];
>>  static DEFINE_SPINLOCK(gpmc_mem_lock);
>> @@ -386,6 +391,63 @@ void gpmc_cs_free(int cs)
>>  }
>>  EXPORT_SYMBOL(gpmc_cs_free);
>>
>> +/**
>> + * gpmc_prefetch_enable - configures and starts prefetch transfer
>> + * @cs: nand cs (chip select) number
>> + * @dma_mode: dma mode enable (1) or disable (0)
>> + * @u32_count: number of bytes to be transferred
>> + * @is_write: prefetch read(0) or write post(1) mode
>> + */
>> +int gpmc_prefetch_enable(int cs, int dma_mode,
>> +                             unsigned int u32_count, int is_write)
>> +{
>> +     uint32_t prefetch_config1;
>> +
>> +     if (!(gpmc_read_reg(GPMC_PREFETCH_CONTROL))) {
>> +             /* Set the amount of bytes to be prefetched */
>> +             gpmc_write_reg(GPMC_PREFETCH_CONFIG2, u32_count);
>> +
>> +             /* Set dma/mpu mode, the prefetch read / post write and
>> +              * enable the engine. Set which cs is has requested for.
>> +              */
>> +             prefetch_config1 = ((cs << CS_NUM_SHIFT) |
>> +                                     PREFETCH_FIFOTHRESHOLD |
>> +                                     ENABLE_PREFETCH |
>> +                                     (dma_mode << DMA_MPU_MODE) |
>> +                                     (0x1 & is_write));
>> +             gpmc_write_reg(GPMC_PREFETCH_CONFIG1, prefetch_config1);
>> +     } else {
>> +             return -EBUSY;
>> +     }
>> +     /*  Start the prefetch engine */
>> +     gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x1);
>> +
>> +     return 0;
>> +}
>> +EXPORT_SYMBOL(gpmc_prefetch_enable);
>> +
>> +/**
>> + * gpmc_prefetch_reset - disables and stops the prefetch engine
>> + */
>> +void gpmc_prefetch_reset(void)
>> +{
>> +     /* Stop the PFPW engine */
>> +     gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x0);
>> +
>> +     /* Reset/disable the PFPW engine */
>> +     gpmc_write_reg(GPMC_PREFETCH_CONFIG1, 0x0);
>> +}
>> +EXPORT_SYMBOL(gpmc_prefetch_reset);
>> +
>> +/**
>> + * gpmc_prefetch_status - reads prefetch status of engine
>> + */
>> +int  gpmc_prefetch_status(void)
>> +{
>> +     return gpmc_read_reg(GPMC_PREFETCH_STATUS);
>> +}
>> +EXPORT_SYMBOL(gpmc_prefetch_status);
>> +
>>  static void __init gpmc_mem_init(void)
>>  {
>>       int cs;
>> @@ -452,6 +514,5 @@ void __init gpmc_init(void)
>>       l &= 0x03 << 3;
>>       l |= (0x02 << 3) | (1 << 0);
>>       gpmc_write_reg(GPMC_SYSCONFIG, l);
>> -
>>       gpmc_mem_init();
>>  }
>> Index: mtd-2.6/arch/arm/plat-omap/include/mach/gpmc.h
>> ===================================================================
>> --- mtd-2.6.orig/arch/arm/plat-omap/include/mach/gpmc.h
>> +++ mtd-2.6/arch/arm/plat-omap/include/mach/gpmc.h
>> @@ -103,6 +103,10 @@ extern int gpmc_cs_request(int cs, unsig
>>  extern void gpmc_cs_free(int cs);
>>  extern int gpmc_cs_set_reserved(int cs, int reserved);
>>  extern int gpmc_cs_reserved(int cs);
>> +extern int gpmc_prefetch_enable(int cs, int dma_mode,
>> +                                     unsigned int u32_count, int is_write);
>> +extern void gpmc_prefetch_reset(void);
>> +extern int gpmc_prefetch_status(void);
>>  extern void __init gpmc_init(void);
>>
>>  #endif
>> Index: mtd-2.6/drivers/mtd/nand/Kconfig
>> ===================================================================
>> --- mtd-2.6.orig/drivers/mtd/nand/Kconfig
>> +++ mtd-2.6/drivers/mtd/nand/Kconfig
>> @@ -80,6 +80,14 @@ config MTD_NAND_OMAP2
>>       help
>>            Support for NAND flash on Texas Instruments OMAP2 and OMAP3 platforms.
>>
>> +config MTD_NAND_OMAP_PREFETCH
>> +     bool "GPMC prefetch support for NAND Flash device"
>> +     depends on MTD_NAND && MTD_NAND_OMAP2
>> +     default y
>> +     help
>> +      The NAND device can be accessed for Read/Write using GPMC PREFETCH engine
>> +      to improve the performance.
>> +
>>  config MTD_NAND_TS7250
>>       tristate "NAND Flash device on TS-7250 board"
>>       depends on MACH_TS72XX
>> Index: mtd-2.6/drivers/mtd/nand/omap2.c
>> ===================================================================
>> --- mtd-2.6.orig/drivers/mtd/nand/omap2.c
>> +++ mtd-2.6/drivers/mtd/nand/omap2.c
>> @@ -112,6 +112,16 @@
>>  static const char *part_probes[] = { "cmdlinepart", NULL };
>>  #endif
>>
>> +#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
>> +static int use_prefetch = 1;
>> +
>> +/* "modprobe ... use_prefetch=0" etc */
>> +module_param(use_prefetch, bool, 0);
>> +MODULE_PARM_DESC(use_prefetch, "enable/disable use of PREFETCH");
>> +#else
>> +const int use_prefetch;
>> +#endif
>> +
>>  struct omap_nand_info {
>>       struct nand_hw_control          controller;
>>       struct omap_nand_platform_data  *pdata;
>> @@ -124,6 +134,7 @@ struct omap_nand_info {
>>       unsigned long                   phys_base;
>>       void __iomem                    *gpmc_cs_baseaddr;
>>       void __iomem                    *gpmc_baseaddr;
>> +     void __iomem                    *nand_pref_fifo_add;
>>  };
>>
>>  /**
>> @@ -189,6 +200,38 @@ static void omap_hwcontrol(struct mtd_in
>>  }
>>
>>  /**
>> + * omap_read_buf8 - read data from NAND controller into buffer
>> + * @mtd: MTD device structure
>> + * @buf: buffer to store date
>> + * @len: number of bytes to read
>> + */
>> +static void omap_read_buf8(struct mtd_info *mtd, u_char *buf, int len)
>> +{
>> +     struct nand_chip *nand = mtd->priv;
>> +
>> +     ioread8_rep(nand->IO_ADDR_R, buf, len);
>> +}
>> +
>> +/**
>> + * omap_write_buf8 - write buffer to NAND controller
>> + * @mtd: MTD device structure
>> + * @buf: data buffer
>> + * @len: number of bytes to write
>> + */
>> +static void omap_write_buf8(struct mtd_info *mtd, const u_char *buf, int len)
>> +{
>> +     struct omap_nand_info *info = container_of(mtd,
>> +                                             struct omap_nand_info, mtd);
>> +     u_char *p = (u_char *)buf;
>> +
>> +     while (len--) {
>> +             iowrite8(*p++, info->nand.IO_ADDR_W);
>> +             while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
>> +                                             GPMC_STATUS) & GPMC_BUF_FULL));
>> +     }
>> +}
>> +
>> +/**
>>   * omap_read_buf16 - read data from NAND controller into buffer
>>   * @mtd: MTD device structure
>>   * @buf: buffer to store date
>> @@ -198,7 +241,7 @@ static void omap_read_buf16(struct mtd_i
>>  {
>>       struct nand_chip *nand = mtd->priv;
>>
>> -     __raw_readsw(nand->IO_ADDR_R, buf, len / 2);
>> +     ioread16_rep(nand->IO_ADDR_R, buf, len / 2);
>>  }
>>
>>  /**
>> @@ -217,13 +260,101 @@ static void omap_write_buf16(struct mtd_
>>       len >>= 1;
>>
>>       while (len--) {
>> -             writew(*p++, info->nand.IO_ADDR_W);
>> +             iowrite16(*p++, info->nand.IO_ADDR_W);
>>
>>               while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
>>                                               GPMC_STATUS) & GPMC_BUF_FULL))
>>                       ;
>>       }
>>  }
>> +
>> +/**
>> + * omap_read_buf_pref - read data from NAND controller into buffer
>> + * @mtd: MTD device structure
>> + * @buf: buffer to store date
>> + * @len: number of bytes to read
>> + */
>> +static void omap_read_buf_pref(struct mtd_info *mtd, u_char *buf, int len)
>> +{
>> +     struct omap_nand_info *info = container_of(mtd,
>> +                                             struct omap_nand_info, mtd);
>> +     uint32_t pfpw_status = 0, r_count = 0;
>> +     int ret = 0;
>> +     u32 *p = (u32 *)buf;
>> +
>> +     /* take care of subpage reads */
>> +     for (; len % 4 != 0; ) {
>> +             *buf++ = __raw_readb(info->nand.IO_ADDR_R);
>> +             len--;
>> +     }
>> +     p = (u32 *) buf;
>> +
>> +     /* configure and start prefetch transfer */
>> +     ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
>> +     if (ret) {
>> +             /* PFPW engine is busy, use cpu copy method */
>> +             if (info->nand.options & NAND_BUSWIDTH_16)
>> +                     omap_read_buf16(mtd, buf, len);
>> +             else
>> +                     omap_read_buf8(mtd, buf, len);
>> +     } else {
>> +             do {
>> +                     pfpw_status = gpmc_prefetch_status();
>> +                     r_count = ((pfpw_status >> 24) & 0x7F) >> 2;
>> +                     ioread32_rep(info->nand_pref_fifo_add, p, r_count);
>> +                     p += r_count;
>> +                     len -= r_count << 2;
>> +             } while (len);
>> +
>> +             /* disable and stop the PFPW engine */
>> +             gpmc_prefetch_reset();
>> +     }
>> +}
>> +
>> +/**
>> + * omap_write_buf_pref - write buffer to NAND controller
>> + * @mtd: MTD device structure
>> + * @buf: data buffer
>> + * @len: number of bytes to write
>> + */
>> +static void omap_write_buf_pref(struct mtd_info *mtd,
>> +                                     const u_char *buf, int len)
>> +{
>> +     struct omap_nand_info *info = container_of(mtd,
>> +                                             struct omap_nand_info, mtd);
>> +     uint32_t pfpw_status = 0, w_count = 0;
>> +     int i = 0, ret = 0;
>> +     u16 *p = (u16 *) buf;
>> +
>> +     /* take care of subpage writes */
>> +     if (len % 2 != 0) {
>> +             writeb(*buf, info->nand.IO_ADDR_R);
>> +             p = (u16 *)(buf + 1);
>> +             len--;
>> +     }
>> +
>> +     /*  configure and start prefetch transfer */
>> +     ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x1);
>> +     if (ret) {
>> +             /* PFPW engine is busy, use cpu copy method */
>> +             if (info->nand.options & NAND_BUSWIDTH_16)
>> +                     omap_write_buf16(mtd, buf, len);
>> +             else
>> +                     omap_write_buf8(mtd, buf, len);
>> +     } else {
>> +             pfpw_status = gpmc_prefetch_status();
>> +             while (pfpw_status & 0x3FFF) {
>> +                     w_count = ((pfpw_status >> 24) & 0x7F) >> 1;
>> +                     for (i = 0; (i < w_count) && len; i++, len -= 2)
>> +                             iowrite16(*p++, info->nand_pref_fifo_add);
>> +                     pfpw_status = gpmc_prefetch_status();
>> +             }
>> +
>> +             /* disable and stop the PFPW engine */
>> +             gpmc_prefetch_reset();
>> +     }
>> +}
>> +
>>  /**
>>   * omap_verify_buf - Verify chip data against buffer
>>   * @mtd: MTD device structure
>> @@ -658,17 +789,12 @@ static int __devinit omap_nand_probe(str
>>               err = -ENOMEM;
>>               goto out_release_mem_region;
>>       }
>> +
>>       info->nand.controller = &info->controller;
>>
>>       info->nand.IO_ADDR_W = info->nand.IO_ADDR_R;
>>       info->nand.cmd_ctrl  = omap_hwcontrol;
>>
>> -     /* REVISIT:  only supports 16-bit NAND flash */
>> -
>> -     info->nand.read_buf   = omap_read_buf16;
>> -     info->nand.write_buf  = omap_write_buf16;
>> -     info->nand.verify_buf = omap_verify_buf;
>> -
>>       /*
>>        * If RDY/BSY line is connected to OMAP then use the omap ready
>>        * funcrtion and the generic nand_wait function which reads the status
>> @@ -689,6 +815,23 @@ static int __devinit omap_nand_probe(str
>>                                                               == 0x1000)
>>               info->nand.options  |= NAND_BUSWIDTH_16;
>>
>> +     if (use_prefetch) {
>> +             /* copy the virtual address of nand base for fifo access */
>> +             info->nand_pref_fifo_add = info->nand.IO_ADDR_R;
>> +
>> +             info->nand.read_buf   = omap_read_buf_pref;
>> +             info->nand.write_buf  = omap_write_buf_pref;
>> +     } else {
>> +             if (info->nand.options & NAND_BUSWIDTH_16) {
>> +                     info->nand.read_buf   = omap_read_buf16;
>> +                     info->nand.write_buf  = omap_write_buf16;
>> +             } else {
>> +                     info->nand.read_buf   = omap_read_buf8;
>> +                     info->nand.write_buf  = omap_write_buf8;
>> +             }
>> +     }
>> +     info->nand.verify_buf = omap_verify_buf;
>> +
>>  #ifdef CONFIG_MTD_NAND_OMAP_HWECC
>>       info->nand.ecc.bytes            = 3;
>>       info->nand.ecc.size             = 512;
>> @@ -746,7 +889,7 @@ static int omap_nand_remove(struct platf
>>       platform_set_drvdata(pdev, NULL);
>>       /* Release NAND device, its internal structures and partitions */
>>       nand_release(&info->mtd);
>> -     iounmap(info->nand.IO_ADDR_R);
>> +     iounmap(info->nand_pref_fifo_add);
>>       kfree(&info->mtd);
>>       return 0;
>>  }
>>
>>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-omap" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
Artem Bityutskiy - Aug. 11, 2009, 6:21 a.m.
On 08/11/2009 08:45 AM, vimal singh wrote:
> On Mon, Aug 10, 2009 at 9:57 PM, Tony Lindgren<tony@atomide.com>  wrote:
>> * vimal singh<vimalsingh@ti.com>  [090713 13:56]:
>>> Patch updated for ' ioreadX / iowriteX and ioreadX_rep / iowriteX_rep' as per
>>> David Brownell's comment. I updated 'omap_(read/write)_buf16' fucntions also
>>> for this.
>>>
>>> -vimal
>>>
>>> This patch adds prefetch support to access nand flash in mpu mode.
>>> This patch also adds 8-bit nand support (omap_read/write_buf8).
>>> Prefetch can be used for both 8- and 16-bit devices.
>>>
>>> Signed-off-by: Vimal Singh<vimalsingh@ti.com>
>> Sorry for the delay. I've looked at the GPMC part, and that now looks OK
>> to me. So I'm OK for this to get integrated via the MTD list.
>>
>> Acked-by: Tony Lindgren<tony@atomide.com>
>>
>
> Can you give your ack to below patch too?
>
> http://lists.infradead.org/pipermail/linux-mtd/2009-July/026373.html

I've picked up both of your patches, please, check:
http://git.infradead.org/users/dedekind/l2-mtd-2.6.git/commit/33f48f597315842f39427ee4261cbf82a9afeaf3
http://git.infradead.org/users/dedekind/l2-mtd-2.6.git/commit/b67d52c91b26e97f981f2c292619d31667d5b272
vimal singh - Aug. 11, 2009, 6:29 a.m.
On Tue, Aug 11, 2009 at 11:51 AM, Artem Bityutskiy<dedekind1@gmail.com> wrote:
> On 08/11/2009 08:45 AM, vimal singh wrote:
>>
>> On Mon, Aug 10, 2009 at 9:57 PM, Tony Lindgren<tony@atomide.com>  wrote:
>>>
>>> * vimal singh<vimalsingh@ti.com>  [090713 13:56]:
>>>>
>>>> Patch updated for ' ioreadX / iowriteX and ioreadX_rep / iowriteX_rep'
>>>> as per
>>>> David Brownell's comment. I updated 'omap_(read/write)_buf16' fucntions
>>>> also
>>>> for this.
>>>>
>>>> -vimal
>>>>
>>>> This patch adds prefetch support to access nand flash in mpu mode.
>>>> This patch also adds 8-bit nand support (omap_read/write_buf8).
>>>> Prefetch can be used for both 8- and 16-bit devices.
>>>>
>>>> Signed-off-by: Vimal Singh<vimalsingh@ti.com>
>>>
>>> Sorry for the delay. I've looked at the GPMC part, and that now looks OK
>>> to me. So I'm OK for this to get integrated via the MTD list.
>>>
>>> Acked-by: Tony Lindgren<tony@atomide.com>
>>>
>>
>> Can you give your ack to below patch too?
>>
>> http://lists.infradead.org/pipermail/linux-mtd/2009-July/026373.html
>
> I've picked up both of your patches, please, check:
> http://git.infradead.org/users/dedekind/l2-mtd-2.6.git/commit/33f48f597315842f39427ee4261cbf82a9afeaf3
> http://git.infradead.org/users/dedekind/l2-mtd-2.6.git/commit/b67d52c91b26e97f981f2c292619d31667d5b272
>

Thanks Artem.

> --
> Best Regards,
> Artem Bityutskiy (Артём Битюцкий)
>
vimal singh - Sept. 5, 2009, 10:06 a.m.
Hi David,


On Tue, Aug 11, 2009 at 11:59 AM, vimal singh<vimal.newwork@gmail.com> wrote:
> On Tue, Aug 11, 2009 at 11:51 AM, Artem Bityutskiy<dedekind1@gmail.com> wrote:
>> On 08/11/2009 08:45 AM, vimal singh wrote:
>>>
>>> On Mon, Aug 10, 2009 at 9:57 PM, Tony Lindgren<tony@atomide.com>  wrote:
>>>>
>>>> * vimal singh<vimalsingh@ti.com>  [090713 13:56]:
>>>>>
>>>>> Patch updated for ' ioreadX / iowriteX and ioreadX_rep / iowriteX_rep'
>>>>> as per
>>>>> David Brownell's comment. I updated 'omap_(read/write)_buf16' fucntions
>>>>> also
>>>>> for this.
>>>>>
>>>>> -vimal
>>>>>
>>>>> This patch adds prefetch support to access nand flash in mpu mode.
>>>>> This patch also adds 8-bit nand support (omap_read/write_buf8).
>>>>> Prefetch can be used for both 8- and 16-bit devices.
>>>>>
>>>>> Signed-off-by: Vimal Singh<vimalsingh@ti.com>
>>>>
>>>> Sorry for the delay. I've looked at the GPMC part, and that now looks OK
>>>> to me. So I'm OK for this to get integrated via the MTD list.
>>>>
>>>> Acked-by: Tony Lindgren<tony@atomide.com>
>>>>
>>>
>>> Can you give your ack to below patch too?
>>>
>>> http://lists.infradead.org/pipermail/linux-mtd/2009-July/026373.html
>>
>> I've picked up both of your patches, please, check:
>> http://git.infradead.org/users/dedekind/l2-mtd-2.6.git/commit/33f48f597315842f39427ee4261cbf82a9afeaf3
>> http://git.infradead.org/users/dedekind/l2-mtd-2.6.git/commit/b67d52c91b26e97f981f2c292619d31667d5b272
>>
>
Is there any chance for these patches to get merged in this merge
window? These have been waiting for long time.

-Vimal

> Thanks Artem.
>
>> --
>> Best Regards,
>> Artem Bityutskiy (Артём Битюцкий)
>>
>

Patch

Index: mtd-2.6/arch/arm/mach-omap2/gpmc.c
===================================================================
--- mtd-2.6.orig/arch/arm/mach-omap2/gpmc.c
+++ mtd-2.6/arch/arm/mach-omap2/gpmc.c
@@ -57,6 +57,11 @@ 
 #define GPMC_CHUNK_SHIFT	24		/* 16 MB */
 #define GPMC_SECTION_SHIFT	28		/* 128 MB */

+#define PREFETCH_FIFOTHRESHOLD	(0x40 << 8)
+#define CS_NUM_SHIFT		24
+#define ENABLE_PREFETCH		(0x1 << 7)
+#define DMA_MPU_MODE		2
+
 static struct resource	gpmc_mem_root;
 static struct resource	gpmc_cs_mem[GPMC_CS_NUM];
 static DEFINE_SPINLOCK(gpmc_mem_lock);
@@ -386,6 +391,63 @@  void gpmc_cs_free(int cs)
 }
 EXPORT_SYMBOL(gpmc_cs_free);

+/**
+ * gpmc_prefetch_enable - configures and starts prefetch transfer
+ * @cs: nand cs (chip select) number
+ * @dma_mode: dma mode enable (1) or disable (0)
+ * @u32_count: number of bytes to be transferred
+ * @is_write: prefetch read(0) or write post(1) mode
+ */
+int gpmc_prefetch_enable(int cs, int dma_mode,
+				unsigned int u32_count, int is_write)
+{
+	uint32_t prefetch_config1;
+
+	if (!(gpmc_read_reg(GPMC_PREFETCH_CONTROL))) {
+		/* Set the amount of bytes to be prefetched */
+		gpmc_write_reg(GPMC_PREFETCH_CONFIG2, u32_count);
+
+		/* Set dma/mpu mode, the prefetch read / post write and
+		 * enable the engine. Set which cs is has requested for.
+		 */
+		prefetch_config1 = ((cs << CS_NUM_SHIFT) |
+					PREFETCH_FIFOTHRESHOLD |
+					ENABLE_PREFETCH |
+					(dma_mode << DMA_MPU_MODE) |
+					(0x1 & is_write));
+		gpmc_write_reg(GPMC_PREFETCH_CONFIG1, prefetch_config1);
+	} else {
+		return -EBUSY;
+	}
+	/*  Start the prefetch engine */
+	gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x1);
+
+	return 0;
+}
+EXPORT_SYMBOL(gpmc_prefetch_enable);
+
+/**
+ * gpmc_prefetch_reset - disables and stops the prefetch engine
+ */
+void gpmc_prefetch_reset(void)
+{
+	/* Stop the PFPW engine */
+	gpmc_write_reg(GPMC_PREFETCH_CONTROL, 0x0);
+
+	/* Reset/disable the PFPW engine */
+	gpmc_write_reg(GPMC_PREFETCH_CONFIG1, 0x0);
+}
+EXPORT_SYMBOL(gpmc_prefetch_reset);
+
+/**
+ * gpmc_prefetch_status - reads prefetch status of engine
+ */
+int  gpmc_prefetch_status(void)
+{
+	return gpmc_read_reg(GPMC_PREFETCH_STATUS);
+}
+EXPORT_SYMBOL(gpmc_prefetch_status);
+
 static void __init gpmc_mem_init(void)
 {
 	int cs;
@@ -452,6 +514,5 @@  void __init gpmc_init(void)
 	l &= 0x03 << 3;
 	l |= (0x02 << 3) | (1 << 0);
 	gpmc_write_reg(GPMC_SYSCONFIG, l);
-
 	gpmc_mem_init();
 }
Index: mtd-2.6/arch/arm/plat-omap/include/mach/gpmc.h
===================================================================
--- mtd-2.6.orig/arch/arm/plat-omap/include/mach/gpmc.h
+++ mtd-2.6/arch/arm/plat-omap/include/mach/gpmc.h
@@ -103,6 +103,10 @@  extern int gpmc_cs_request(int cs, unsig
 extern void gpmc_cs_free(int cs);
 extern int gpmc_cs_set_reserved(int cs, int reserved);
 extern int gpmc_cs_reserved(int cs);
+extern int gpmc_prefetch_enable(int cs, int dma_mode,
+					unsigned int u32_count, int is_write);
+extern void gpmc_prefetch_reset(void);
+extern int gpmc_prefetch_status(void);
 extern void __init gpmc_init(void);

 #endif
Index: mtd-2.6/drivers/mtd/nand/Kconfig
===================================================================
--- mtd-2.6.orig/drivers/mtd/nand/Kconfig
+++ mtd-2.6/drivers/mtd/nand/Kconfig
@@ -80,6 +80,14 @@  config MTD_NAND_OMAP2
 	help
           Support for NAND flash on Texas Instruments OMAP2 and OMAP3 platforms.

+config MTD_NAND_OMAP_PREFETCH
+	bool "GPMC prefetch support for NAND Flash device"
+	depends on MTD_NAND && MTD_NAND_OMAP2
+	default y
+	help
+	 The NAND device can be accessed for Read/Write using GPMC PREFETCH engine
+	 to improve the performance.
+
 config MTD_NAND_TS7250
 	tristate "NAND Flash device on TS-7250 board"
 	depends on MACH_TS72XX
Index: mtd-2.6/drivers/mtd/nand/omap2.c
===================================================================
--- mtd-2.6.orig/drivers/mtd/nand/omap2.c
+++ mtd-2.6/drivers/mtd/nand/omap2.c
@@ -112,6 +112,16 @@ 
 static const char *part_probes[] = { "cmdlinepart", NULL };
 #endif

+#ifdef CONFIG_MTD_NAND_OMAP_PREFETCH
+static int use_prefetch = 1;
+
+/* "modprobe ... use_prefetch=0" etc */
+module_param(use_prefetch, bool, 0);
+MODULE_PARM_DESC(use_prefetch, "enable/disable use of PREFETCH");
+#else
+const int use_prefetch;
+#endif
+
 struct omap_nand_info {
 	struct nand_hw_control		controller;
 	struct omap_nand_platform_data	*pdata;
@@ -124,6 +134,7 @@  struct omap_nand_info {
 	unsigned long			phys_base;
 	void __iomem			*gpmc_cs_baseaddr;
 	void __iomem			*gpmc_baseaddr;
+	void __iomem			*nand_pref_fifo_add;
 };

 /**
@@ -189,6 +200,38 @@  static void omap_hwcontrol(struct mtd_in
 }

 /**
+ * omap_read_buf8 - read data from NAND controller into buffer
+ * @mtd: MTD device structure
+ * @buf: buffer to store date
+ * @len: number of bytes to read
+ */
+static void omap_read_buf8(struct mtd_info *mtd, u_char *buf, int len)
+{
+	struct nand_chip *nand = mtd->priv;
+
+	ioread8_rep(nand->IO_ADDR_R, buf, len);
+}
+
+/**
+ * omap_write_buf8 - write buffer to NAND controller
+ * @mtd: MTD device structure
+ * @buf: data buffer
+ * @len: number of bytes to write
+ */
+static void omap_write_buf8(struct mtd_info *mtd, const u_char *buf, int len)
+{
+	struct omap_nand_info *info = container_of(mtd,
+						struct omap_nand_info, mtd);
+	u_char *p = (u_char *)buf;
+
+	while (len--) {
+		iowrite8(*p++, info->nand.IO_ADDR_W);
+		while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
+						GPMC_STATUS) & GPMC_BUF_FULL));
+	}
+}
+
+/**
  * omap_read_buf16 - read data from NAND controller into buffer
  * @mtd: MTD device structure
  * @buf: buffer to store date
@@ -198,7 +241,7 @@  static void omap_read_buf16(struct mtd_i
 {
 	struct nand_chip *nand = mtd->priv;

-	__raw_readsw(nand->IO_ADDR_R, buf, len / 2);
+	ioread16_rep(nand->IO_ADDR_R, buf, len / 2);
 }

 /**
@@ -217,13 +260,101 @@  static void omap_write_buf16(struct mtd_
 	len >>= 1;

 	while (len--) {
-		writew(*p++, info->nand.IO_ADDR_W);
+		iowrite16(*p++, info->nand.IO_ADDR_W);

 		while (GPMC_BUF_EMPTY == (readl(info->gpmc_baseaddr +
 						GPMC_STATUS) & GPMC_BUF_FULL))
 			;
 	}
 }
+
+/**
+ * omap_read_buf_pref - read data from NAND controller into buffer
+ * @mtd: MTD device structure
+ * @buf: buffer to store date
+ * @len: number of bytes to read
+ */
+static void omap_read_buf_pref(struct mtd_info *mtd, u_char *buf, int len)
+{
+	struct omap_nand_info *info = container_of(mtd,
+						struct omap_nand_info, mtd);
+	uint32_t pfpw_status = 0, r_count = 0;
+	int ret = 0;
+	u32 *p = (u32 *)buf;
+
+	/* take care of subpage reads */
+	for (; len % 4 != 0; ) {
+		*buf++ = __raw_readb(info->nand.IO_ADDR_R);
+		len--;
+	}
+	p = (u32 *) buf;
+
+	/* configure and start prefetch transfer */
+	ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
+	if (ret) {
+		/* PFPW engine is busy, use cpu copy method */
+		if (info->nand.options & NAND_BUSWIDTH_16)
+			omap_read_buf16(mtd, buf, len);
+		else
+			omap_read_buf8(mtd, buf, len);
+	} else {
+		do {
+			pfpw_status = gpmc_prefetch_status();
+			r_count = ((pfpw_status >> 24) & 0x7F) >> 2;
+			ioread32_rep(info->nand_pref_fifo_add, p, r_count);
+			p += r_count;
+			len -= r_count << 2;
+		} while (len);
+
+		/* disable and stop the PFPW engine */
+		gpmc_prefetch_reset();
+	}
+}
+
+/**
+ * omap_write_buf_pref - write buffer to NAND controller
+ * @mtd: MTD device structure
+ * @buf: data buffer
+ * @len: number of bytes to write
+ */
+static void omap_write_buf_pref(struct mtd_info *mtd,
+					const u_char *buf, int len)
+{
+	struct omap_nand_info *info = container_of(mtd,
+						struct omap_nand_info, mtd);
+	uint32_t pfpw_status = 0, w_count = 0;
+	int i = 0, ret = 0;
+	u16 *p = (u16 *) buf;
+
+	/* take care of subpage writes */
+	if (len % 2 != 0) {
+		writeb(*buf, info->nand.IO_ADDR_R);
+		p = (u16 *)(buf + 1);
+		len--;
+	}
+
+	/*  configure and start prefetch transfer */
+	ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x1);
+	if (ret) {
+		/* PFPW engine is busy, use cpu copy method */
+		if (info->nand.options & NAND_BUSWIDTH_16)
+			omap_write_buf16(mtd, buf, len);
+		else
+			omap_write_buf8(mtd, buf, len);
+	} else {
+		pfpw_status = gpmc_prefetch_status();
+		while (pfpw_status & 0x3FFF) {
+			w_count = ((pfpw_status >> 24) & 0x7F) >> 1;
+			for (i = 0; (i < w_count) && len; i++, len -= 2)
+				iowrite16(*p++, info->nand_pref_fifo_add);
+			pfpw_status = gpmc_prefetch_status();
+		}
+
+		/* disable and stop the PFPW engine */
+		gpmc_prefetch_reset();
+	}
+}
+
 /**
  * omap_verify_buf - Verify chip data against buffer
  * @mtd: MTD device structure
@@ -658,17 +789,12 @@  static int __devinit omap_nand_probe(str
 		err = -ENOMEM;
 		goto out_release_mem_region;
 	}
+
 	info->nand.controller = &info->controller;

 	info->nand.IO_ADDR_W = info->nand.IO_ADDR_R;
 	info->nand.cmd_ctrl  = omap_hwcontrol;

-	/* REVISIT:  only supports 16-bit NAND flash */
-
-	info->nand.read_buf   = omap_read_buf16;
-	info->nand.write_buf  = omap_write_buf16;
-	info->nand.verify_buf = omap_verify_buf;
-
 	/*
 	 * If RDY/BSY line is connected to OMAP then use the omap ready
 	 * funcrtion and the generic nand_wait function which reads the status
@@ -689,6 +815,23 @@  static int __devinit omap_nand_probe(str
 								== 0x1000)
 		info->nand.options  |= NAND_BUSWIDTH_16;

+	if (use_prefetch) {
+		/* copy the virtual address of nand base for fifo access */
+		info->nand_pref_fifo_add = info->nand.IO_ADDR_R;
+
+		info->nand.read_buf   = omap_read_buf_pref;
+		info->nand.write_buf  = omap_write_buf_pref;
+	} else {
+		if (info->nand.options & NAND_BUSWIDTH_16) {
+			info->nand.read_buf   = omap_read_buf16;
+			info->nand.write_buf  = omap_write_buf16;
+		} else {
+			info->nand.read_buf   = omap_read_buf8;
+			info->nand.write_buf  = omap_write_buf8;
+		}
+	}
+	info->nand.verify_buf = omap_verify_buf;
+
 #ifdef CONFIG_MTD_NAND_OMAP_HWECC
 	info->nand.ecc.bytes		= 3;
 	info->nand.ecc.size		= 512;
@@ -746,7 +889,7 @@  static int omap_nand_remove(struct platf
 	platform_set_drvdata(pdev, NULL);
 	/* Release NAND device, its internal structures and partitions */
 	nand_release(&info->mtd);
-	iounmap(info->nand.IO_ADDR_R);
+	iounmap(info->nand_pref_fifo_add);
 	kfree(&info->mtd);
 	return 0;
 }